CAPE CANAVERAL, Fla. — NASA said Thursday that the shuttle will remain grounded for more than a year longer, and once launches do resume, a second spaceship will be on standby to rescue the astronauts if their craft is damaged in flight.

Because of the Columbia disaster one year ago, NASA decided last month that all shuttles from now on will be devoted to completing the international space station. That way, the astronauts can inspect and repair their ships at the orbiting outpost and await rescue there if the damage is too grave.

The rescue shuttle will not necessarily be on the launch pad, but will be ready to fly to the space station within 45 to 90 days, shuttle program manager Bill Parsons said. That is how long seven additional astronauts could remain aboard the space station before food, oxygen and other supplies ran out.

No earlier than March 2005
NASA had been aiming for its first post-Columbia launch as early as next fall, but senior spaceflight officials decided to bump the flight to no earlier than March 2005. Because of a new safety requirement for daylight launches to photograph the liftoff from multiple angles, the space agency is limited in the number of days it can send a shuttle to the station, and a long window runs from early March to mid-April 2005.

Officials also decided to fly Discovery on the first post-Columbia mission and have Atlantis on standby. Shuttle flights, along with space station construction, have been on hold since Columbia shattered over Texas on Feb. 1, 2003.

This will be the first time the space agency has had a rescue ship waiting in the wings since the days of NASA’s first space station, Skylab, in the 1970s.

How long will standbys be needed?NASA deputy associate administrator Michael Kostelnik said it is too soon to say whether a shuttle will be on standby for succeeding missions as well.

“I don’t believe that there’s an awful lot of extra training or extra things that we have to do for a rescue mission,” Parsons said. “It would just be going to the international space station, docking, picking up crew, making sure that we had the appropriate hardware and different things that we needed to bring that crew on board and then return safely.”

In the case of Columbia, such a rescue would have been impossible. The shuttle did not visit the space station; it was in an orbit entirely different from that of the station and lacked the fuel to get there.

Any shuttle sent to Columbia’s aid would have had to fly in formation, and spacewalks would have been needed to transfer Columbia’s seven astronauts to the rescue ship.

Numerous changes on tap
Discovery will incorporate numerous changes for the first shuttle flight since Columbia, including improvements to the external fuel tank and the leading edges of the wings. The changes were prompted by the Columbia accident, in which a piece of foam broke off from the external tank during launch and damaged the wing, dooming the spacecraft during re-entry.

“We’re certainly interested in reducing the risk,” Kostelnik said. Having a shuttle on standby will provide “added robustness,” he added.

As many as 35 more shuttle missions are needed to finish building the space station.

NASA recently canceled one last servicing mission to the Hubble Space Telescope and consigned it to an early death because a shuttle could not fly from Hubble to the space station in an emergency. The space agency decided it was not worth risking astronauts’ lives to service the telescope.

Struggling with problems
The space agency is still struggling to come up with shuttle wing repair kits and inspection booms for astronauts in orbit. In addition, engineers are still trying to figure out how to keep the fuel-tank foam insulation from breaking off, and looking for possible corrosion in the rudder speed brakes.

“We said, ‘Stop.’ Let’s go ahead and extend the (launch) schedule and let’s figure out what the right way is to go about” meeting the recommendations of the Columbia accident investigators, NASA Administrator Sean O’Keefe said during a visit to Orlando, Fla. “We’re not going to be driven by the calendar. This is going to be a milestone-driven event.”